Cosmic Curvature (standard ruler)

Some of the most important parameters of the metric are those that directly affect the curvature of three-dimensional comoving spatial sections. This mainly includes and . The first (and possibly the only, so far) simultaneous constraint on both and from within a single survey, using a standard ruler method, is AstroPh:0106135 - Roukema, Mamon, Bajtlik (2002). This topic is generally referred to today as BAO - the use of baryonic acoustic oscillations - although in fact can be more general, i.e. make less assumptions. The best-cited example of BAO usage is AstroPh:0501171 SDSS z < 0.47 Eisenstein et al., who estimated Omega_total = 1.010\pm0.009. Updating Roukema, Mamon & Bajtlik (2002) on newer QSO redshift surveys should result in preciser, and hopefully more accurate, estimates of these metric parameters.